Do not remove work tile from inside the tile.

AutoAddable will take care of removing it for the correct user, as it
gets its user from CurrentTilesInteractor.

Also, fix user switch in CurrentTilesInteractor. It was triggering more
often than it should.

Test: manual
Fixes: 352008994
Flag: EXEMPT bugfix
Change-Id: If1b66e06649566335ee904e3d40f11cc3c921064